Shavelenka (English Motion blur, also "blur", "shaking off", "twitching") - a photographic defect, blurred image (blur, often with two or more sharper phases) caused by the movement of the subject or camera at the time of exposure ...
Sometimes the terms "shake" and "shaking the frame" are delineated, and they are given their own semantic shades: "shake" is used in relation to the movement of the objects themselves in the frame, while "twitching" or "shaking off" - to the movement of the camera. However, the reverse use is possible. This set of terms for describing the phenomenon is not well-established, discrepancies are possible.
At the initial stage of the development of photography, format cameras were large and heavy, and photography, as a rule, was carried out from a tripod, which excluded the movement of the apparatus, and the low sensitivity of photographic materials neutralized camera shake from shutter or the touch of a photographer. However, the same low sensitivity required a large exposure and made the shooting sensitive to the movements of the subjects (it was at this stage that the traditional words of the photographer appeared: "Don't move! Now a bird will fly out!").
With an increase in the sensitivity of photographic materials, the requirements for shooting objects decrease, but shooting becomes more sensitive to camera shake from the photographer's touch (to exclude which a cable was used for triggering) and triggering shutter... The best results were obtained when photographing with cameras with a central gateohm due to the lower mass of the moving parts and the symmetry of the displacements about the axis lens.
With the advent of SLR cameras (medium format), another source of camera vibrations appeared - camera shake when raising a mirror, which had a significant mass. So, cameras "Salyut" of the first issues had an unbalanced drive shutter and a mirror, which made photography much more difficult. With a further reduction in the size of the mirror in SLR cameras of smaller formats and the use of various methods of suppressing the negative effect of mirror uplift, we can distinguish only when using telephoto lenses.
With the decrease in the size of cameras, the main reason for the "shake" was shooting "handheld" as a result of their natural shake and lowering of the camera as a result of pressing the shutter button and returning when released. With the decrease in the weight of the camera, this factor only exacerbated. Another factor that increased the "shake" was the abandonment of optical viewfinders, which served as an additional point of support for the photographer, in favor of aiming at the LCD screen of modern digital cameras.
Many modern digital cameras warn the photographer about a shutter speed that is not fast enough for handheld shooting with a special icon (a palm image, an icon showing a shaking camera, etc.) and / or highlighting the exposure meter data in red.
How to avoid "stirring" and "smearing"
All these methods are aimed at eliminating (reducing) or compensating for the movements of the camera and the subject, or the effect of them.
Decrease shutter speed.
It should be mentioned separately, because, unlike all other methods, they are able to reduce the effect of movement not only of the camera, but also of the subject of photography:
- Application of photographic materials (or mode) of higher sensitivity and / or optics of higher aperture
- The use of additional lighting, including a photo flash. When shooting with flash in low light excerpt not determined by opening time shutter, and the glow time of the flash lamp, which is about 1/1000 sec, therefore, such images practically do not suffer from shake - in such a short time the camera does not have time to significantly change its position. Despite this, for the remaining opening time shutter bright moving objects can be exposed and be visible as a trail from the main image. To reduce this effect, designers of photographic gateov tend to reduce the shutter speed at which gate fully open, and also introduces high-speed sync mechanisms with flash lamps. Artistic use of the effect to show the movement of the subject is achieved by selecting the rear-curtain flash sync mode.
Common shooting techniques to reduce hand shake and impact on the camera, such as shooting from a comfortable position, holding the camera firmly, using a "contact" viewfinder, avoiding a sharp press and release of the shutter button (including the use of the self-timer), holding the breath for a while exposure, etc.
Using additional or improved support (in addition to the arms)
- Various improvised supports (trees, railings, etc.).
Photogun: a stock with a stock, on which the camera is attached. Some types of tabletop tripods can be turned into makeshift photographic guns.
"Flexible tripod": a screw is screwed into the tripod socket, to which a cord or chain of suitable length is attached. When you need to fix the camera, they put their feet on the lace and pull it.
Monopod: telescopic rod with camera mount. Provides the photographer with more mobility than a tripod. In fact, the "monopod and two photographer's legs" system forms the same three-legged tripod.
- Using a tripod without fixing the apparatus.
- Image stabilizer: a device in a camera that allows you to compensate for small movements of the camera by symmetrical displacement of a lens group or photosensor. According to the most optimistic data, the gain in the value of the allowable exposure is 8-16 times (3-4 stops of exposure). When shooting with a fixed camera, stabilization often needs to be turned off to avoid false detection. Electronic (or digital) stabilization, common in television and video cameras, is not applicable for ordinary digital cameras (performing one readout from a photosensor).
Fixing the position of the device using various devices
- Tripod. Provides the best camera stability over the entire exposure range, up to hours and days.
- Table tripod: Designed for situations where a conventional tripod is too bulky.
- Clamp: unlike a tabletop tripod, it does not stand on the table, but is screwed onto the table. Provides better camera fixation, indispensable for shooting experiments performed on the table. The clamp can also be screwed to a chair, bench, rail, etc.
- Steadicam, gyroscopic stabilizer, gyro platform. A device containing a gyroscope (possibly two or three), a gyroscope axis fixing unit, a damping unit, and a mount for shooting equipment. Maintains the direction of the optical axis lensusing the gyroscopic effect. When cropping, the gyroscope axis is free, and the device can be rotated to any position. At the time of shooting, the platform is fixed relative to the gyroscope axis. The disadvantage of the system is high power consumption and cost.
- The use of a non-contact release (mainly when the camera is fixed or partially fixed) is intended to exclude the influence of the photographer's hands when the shutter is pressed. The photographer presses the remote control button with his free hand or teeth . A release cord is a mechanical or electrical device attached to the start button or a special connector on the camera, pressing the button on which triggers shutter camera . In the mechanical version, it is a flexible metal tube up to 40 cm long with a flexible rod inside. On one side of the cable there is a push button. On the other hand, there is a tapered thread for screwing into the hole of the release button.
- The remote control of the descent is usually infrared.
- Self-timer - mechanical or electronic device of the camera for delaying the moment of release shutter.
- Pre-lifting the mirror - a technique that ensures the mirror is raised some time before the descent shutter... The pause is made in order to avoid vibration of the camera from the "clap" of the mirror during the exposure.
- Taking multiple shots (sequential shooting, burst mode, or bracketinga) with the subsequent choice of the most clear. With continuous shooting, for example, the first shots may be more wiggly than the subsequent ones. Some digital cameras take several shots at once and allow you to choose the most successful one (Olympus Camedia E-100RS) or make this choice yourself (Nikon Coolpix P5000).